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971.
972.
The massive publicity surrounding the exodus of residents from New Orleans spurred by Hurricane Katrina has encouraged interest in the ways that past migration in the U.S. has been shaped by environmental factors. So has Timothy Egan’s exciting book, The Worst Hard Time: The Untold Story of those who survived the Great American Dust Bowl. This article places those dramatic stories into a much less exciting context, demonstrating that the kinds of environmental factors exemplified by Katrina and the Dust Bowl are dwarfed in importance and frequency by the other ways that environment has both impeded and assisted the forces of migration. We accomplish this goal by enumerating four types of environmental influence on migration in the U.S.: (1) environmental calamities, including floods, hurricanes, earthquakes, and tornadoes, (2) environmental hardships and their obverse, short-term environmental benefits, including both drought and short periods of favorable weather, (3) environmental amenities, including warmth, sun, and proximity to water or mountains, and (4) environmental barriers and their management, including heat, air conditioning, flood control, drainage, and irrigation. In U.S. history, all four of these have driven migration flows in one direction or another. Placing Katrina into this historical context is an important task, both because the environmental calamities of which Katrina is an example are relatively rare and have not had a wide impact, and because focusing on them defers interest from the other kinds of environmental impacts, whose effect on migration may have been stronger and more persistent, though less dramatic. 相似文献
973.
B.J. Hicks S.J. Culley C.A. McMahon P. Powell 《Journal of Engineering and Technology Management》2010,27(1-2):52-73
The benefits of integrated enterprise-wide information systems (IS), such as Enterprise Resource Planning (ERP) systems, are widely accepted. The implementation of such systems in large organisations is established with many in their second or third generation. However, in small to medium-sized enterprises (SMEs) the maturity and extent of their IS infrastructure is less clear. In engineering SMEs, this infrastructure needs to support not only business processes but also the activities of design and manufacture.In this case study, our goal is to provide a better understanding of current IS infrastructure, the functional elements of IS infrastructure, integration and expenditures are explored in ten engineering SMEs. A model of IS functionality is developed and used to identify and classify functional elements within the firms and to compare and contrast the IS infrastructures. The findings are contrasted with the SME literature and conclusions and implications developed. 相似文献
974.
Elizabeth George Claudio Milman Satish P. Deshpande 《International Journal of Value-Based Management》1999,12(2):129-136
This study examines perception of various business practices of Russian and American managers. Using data collected from 136
Russian managers and 252 American managers we found that cross-national differences account for many differences between perceptions
of business practices. Implications for managerial practice are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
975.
A new class of partially efficiency-balanced designs is introduced from a practical point of view. This new design includes all equireplicated incomplete block designs available in literature as special cases. The fundamental properties of the design are clarified with relation to other block designs. 相似文献
976.
Nonparametric tests for the null hypothesis of no treatment effect in the mixed-model experiment which involves n randomly chosen subjects who respond once to each of ρ distinct treatments have been developed by Koch and Sen (1968), These tests were based on the assumption of compound symmetry of the error vectors and on the weaker assumption of diagonal symmetry of the error vectors. This paper considers an alternative (permutationally) distribution-free test under this latter assumption. The new test follows the same type of distribution theory as those in Koch and Sen, but utilizes the inherent invariance structure in a more visable and direct way. 相似文献
977.
R.P. Bhargava 《统计学通讯:理论与方法》2013,42(11):1209-1231
Analysis for univariate and multivariate categorical data in block designs is given and illustrated through examples. The univariate analysis compares the treatments on the basis of their pooled frequency distributions (pooled over blocks). The test statistic used is called Q after Cochran (1950). The large sample null distribution of Q is a chi-square. Analysis of p-variate categorical data (kth variable having ck classes, K=1,...,p) can be done by treating it as a univariate categorical problem with [d] classes. Very often [d] is large in relation to the size of the experiment. This makes the expected frequencies for some of the cells very small, making the univariate method inapplicable. In these circumstances it may be reasonable to compare the treatments on the basis of marginal distributions up to the mth dimension, 1[d] , which is given in this paper. This method is also illustrated for missing observations 相似文献
978.
In the face of administrative and pedagogic changes in professional social work training, educators and trainers face considerable uncertainty. Key dilemmas concern what is meant by competence, and how far it is possible to identify and reconcile technical and ideological competencies. This paper uses empirical material from a semi-participant study to explore the relevance of the concept ‘cloak of competence’, with reference to the behaviour of tutors and practice teachers. It suggests that excessive or continuous uncertainty generates avoidance or coping strategies, which lead to a resolution by the achievement of an appearance of competence. The consequences of these processes for staff development are then briefly considered. 相似文献
979.
980.
A variety of methods of eliciting a prior distribution for a multivariate normal (MVN) distribution have recently been proposed. This paper reports an experiment in which 16 meteorologists used the methods to quantify their opinions about climatology variables. Our results compare prior models and show, in particular, that it can be better to assume the mean and variance of an MVN distribution are independent a priori, rather than to model opinion by the conjugate prior distribution. Using a proper scoring rule, different forms of assessment task are examined and alternative ways of estimating parameters are compared. To quantify opinion about means, it proved preferable to ask directly about the means rather than individual observations while, to quantify opinion about the variance matrix, it was best to ask about deviations from the mean. Further results include recommendations for the way parameters of the prior distribution are estimated. 相似文献